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The patient had residual tumor following the 2018 transsphenoidal resection and underwent an additional surgery after the residual tumor increased in size. Since pituitary adenoma/pituitary neuroendocrine tumor (PitNET) is a new malignant neoplasm for cases diagnosed 2023 and later, should this be a new primary per M5? Or do we disregard the change in behavior and apply rule M2 (single tumor is a single primary) for this scenario?

Disease History

2018 - Lymphomatoid papulosis (non-reportable)

2020 - Transform to CTCL (and called Mycosis Fungoides specifically) (CTCL/MF same primary)

2021 - Transform to CTCL with large cell transformation

Patient had a total abdominal hysterectomy-bilateral salpingo-oophorectomy performed in January 2023 with final diagnosis of myxoid and epithelioid leiomyosarcoma.

Diagnosis comment states: The tumor is 15 cm per report. It grows in nests and poorly formed interanastomosing trabeculae and cords that are separated by abundant myxoid background. The cells have an epithelioid morphology with eosinophilic cytoplasm, large nuclei, and very prominent nucleoli. The mitotic activity is overall low ranging from 1 to 3/10 HPFs.

Immunohistochemical stains performed at the outside hospital showed diffuse positivity for SMA, desmin, caldesmon, and PR. They are negative for CD10, claudin-4, calretinin, HBM45, MART1 (rare weakly positive cells), PANCK, and SOX10. This immunohistochemical profile supports a smooth muscle derivation of this neoplasm. As this tumor is extensively myxoid, diagnostic criteria differ from the spindle cell leiomyosarcoma.

Per Solid Tumor Rules Other Sites, Table 16: Uterine Corpus Histologies, Epithelioid Leiomyosarcoma (8891/3) and Myxoid Leiomyosarcoma (8896/3) are both subtypes of Sarcoma, NOS (8800/3).  Per Rule H21, use a combination code when there are multiple specific histologies AND the combination is listed in Table 2 OR there are coding instructions for the combination in the applicable histology Tables 3-21 OR you receive a combination code from Ask A SEER Registrar.  Since there is no combination listed in Table 2 and there is no instruction for the combination in Table 16, how should the histology be coded for this tumor?

In 2021, the patient was diagnosed with a non-reportable appendiceal LAMN.  Resection showed a tumor diffusely involving the appendix and perforating the visceral peritoneum, as well as extensive intraperitoneal metastasis.  In 2023, a lung wedge resection revealed metastatic mucinous neoplasm involving lung parenchyma and pleura, consistent with metastasis of the known appendiceal primary.  It is understood that intraperitoneal spread of an appendiceal LAMN does not make it reportable because the peritoneal disease is also non-invasive.  Does extraperitoneal metastasis of an appendiceal LAMN diagnosed prior to 2022 make it invasive disease and therefore reportable? 

The resection pathology report final diagnosis indicates this is both mixed mucinous and non-mucinous with a lepidic predominant component. The pathologist notes this is “Lepidic: 75%. Acinar: 25%.”  The percentage of the mucinous component is not documented.

Rule H1, Note 1, states “When mucinous carcinoma is mixed with another histology, such as adenocarcinoma and mucinous carcinoma, code mucinous ONLY when mucinous is documented to be greater than 50% of the tumor.” While mixed invasive mucinous and non-mucinous carcinoma is included in Table 2 (Combination/Mixed Histology Codes) without a required percentage, it is unclear whether one should move past Rule H7 and use Rule H8 to code this combination histology code. Rule H7 would instruct one to code the histology to lepidic adenocarcinoma (adenocarcinoma, lepidic predominant) based on the percentage of the lepidic component in the tumor. However, this does not address the mixed mucinous and non-mucinous diagnosis. Which H Rule and histology apply to this case?

Since the peripheral nerves are included in the Malignant CNS schema of the Solid Tumor Rules, neither the differences in subsite nor timing indicate these are separate primaries (Rule M10 indicates a single primary). However, these are separate MPNSTs in different sites and the tumors are not stated to be metastasis. Additionally, these are treated as separate primaries by the managing physician.

While the malignant CNS tumors do not take timing into account, is this correct for these peripheral nerve tumors that are often treated similarly to soft tissue tumors? Should Rule M8 be updated to include tumors in different peripheral nerve subsites?

Patient had a mandibular mucosal lesion resected in June of 2023, with a diagnosis of “atypical squamous proliferation” and case was forwarded to an expert in oral pathology for best classification. Subsequent slide review final diagnosis was “moderate to severe squamous dysplasia.” That slide review diagnosis goes on to state “microscopic focus suspicious for superficial invasion.”

Currently there is no ICD-O code for severe squamous dysplasia, however it is unclear if this terminology is equivalent to high grade squamous dysplasia (histology code 8077/2).

The patient was diagnosed with a biopsy-proven 12/2020 LUL SCC treated with radiation only, followed by a right hilar lymph node biopsy in 07/2022, that proved “metastatic pulmonary adenocarcinoma” per pathology and treated with radiation, followed by a biopsy-proven 12/2022 RLL SCC to be treated with immunotherapy only. The imaging never definitively identified a lung tumor that can be assumed to be a primary adenocarcinoma tumor.  In 06/2022, a PET scan only described a “strongly PET positive Rt inferior hilar LN vs infrahilar pulmonary mass,” as well as the subsequently biopsy-proven SCC in the RLL (12/2022 SCC primary). The biopsy path indicates this was a right hilar lymph node metastasis and does not indicate this is an infrahilar pulmonary mass. No other PET positive pulmonary lesions were seen at the time.

The oncologist’s assessment indicates the right hilar node was the only positive finding on the biopsy, and it was unclear if this right hilar node metastasis was from the left lung or if the primary was “not detectable.” The oncologist summarized this as a LUL lung lesion radiated for SCC, a right hilar lesion radiated for adenocarcinoma, and a RLL lung lesion on pathology found to be SCC.

Should the interval occurring metastatic adenocarcinoma be accessioned as a separate lung, NOS primary based on the histology difference? While the Solid Tumor Rules do not apply to metastasis, the oncologist did treat these three malignancies separately and does not indicate the hilar lymph node metastasis was felt to be from either SCC primary.

Per Solid Tumor Manual Other Sites Rule M6, despite the number of areas of involvement, any presentation of Kaposi sarcoma is always a single primary. The primary site is skin using the Kaposi Sarcoma for All Sites Coding Guidelines (Appendix C, 2023 SEER Manual). 

Does SEER Program Coding and Staging Manual Laterality Coding Instruction #4 preclude the use of code 4 [Bilateral involvement at time of diagnosis...] if a patient presents with KS involvement of only both arms or only both sides of the face?